Researchers have done electron cooling before, but only when the entire device is immersed into an extremely cold cooling bath.

Seong Jin Koh, an associate professor at UT Arlington and his team used a nano-scale structure -- which consists of a sequential array of a source electrode, a quantum well, a tunneling barrier, a quantum dot, another tunneling barrier, and a drain electrode -- to suppress electron excitation and to make electrons cold.

Electrons are thermally excited even at room temperature, which is a natural phenomenon. If that electron excitation could be suppressed, then the temperature of those electrons could be effectively lowered without external cooling.

Cold electrons promise a new type of transistor that can operate at extremely low-energy consumption and it could help in the fabrication of energy-efficient transistors.